Here's a thought:
While a shield would be impractical to carry around, the phalanx idea still holds strong. Suppose you and a group of fellow hunters are cleaning out a town or city of zombies. The police will probably have already failed, and will have left their riot shields where they dropped them. Assuming you have enough people in your group, half grabbes the shields, and forms a wall. the other half stands behind them, rifles at the ready, and guns down the zombie horde.